AlGaN/GaN high-electron-mobility transistor(HEMT) employing Schottky contact on the unetched region and the silicon dioxide passivation

Abstract

AlGaN/GaN high-electron-mobility transistors (HEMTs) which have the Schottky contact only formed on the unetched region and the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> passivation using an inductively coupled chemical vapor deposition (ICP-CVD) was proposed. The proposed device does not have any Schottky contact on the dry-etched region because the Schottky contact formation is performed prior to the mesa isolation, which suppresses problems induced by the poor interface between the etched region and Schottky metal. The SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> passivation using ICP-CVD suppress the electron trapping in surface states so that improves the reverse characteristics of the passivated device. We have fabricated the AlGaN/GaN HEMT without Schottky contact on the dry-etched region employing the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> passivation using an ICP-CVD and measured the electrical characteristics of the proposed device. The proposed device achieved the on resistance of 3.06 mOmegacm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (at L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> =3 mum, L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GD</sub> =20 mum) and improve the breakdown voltage from 363.0 V to 815.0 V (at L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> =3 mum, L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GD</sub> =20 mum). The figure-of-merit (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> /R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> ) is 217.07 MW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The proposed device removes the poor Schottky contact interface and suppresses the electron trapping at surface states, which results in high breakdown voltage.